Cooling element

ABSTRACT

Cooling element for vacuum pump comprising a base element wherein by the base element an internal void is defined. Further, an inlet is connected to the base element and is in fluent connection with the void. Further, an outlet is connected to the base element and in fluent connection with the void such that a coolant can flow from the inlet through the void to the outlet to dissipated heat. Therein, the base element is connected to a housing of a vacuum pump.

CROSS-REFERENCE OF RELATED APPLICATION

This application is a Section 371 National Stage Application ofInternational Application No. PCT/GB2021/051188, filed May 18, 2021, andpublished as WO 2021/234363A1 on Nov. 25, 2021, the content of which ishereby incorporated by reference in its entirety and which claimspriority of British Application No. 2007489.4, filed May 20, 2020.

BACKGROUND

The present invention relates to a cooling element for a vacuum pump anda vacuum pumping such a cooling element.

The discussion above is merely provided for general backgroundinformation and is not intended to be used as an aid in determining thescope of the claimed subject matter. The claimed subject matter is notlimited to implementations that solve any or all disadvantages noted inthe background.

SUMMARY

Common cooling elements for vacuum pumps are built by pressed in or castin stainless steel pipes in an aluminum block. However, the mating facecontact between aluminum and the stainless steel pipe in the coolingblock is not perfect neither if pressed in or cast into the aluminumblock. Therefore, the thermal transfer from the housing of the vacuumpump to the coolant flowing through the pipe is not sufficient. Further,the thermal transfer is further reduced since usually there is a laminarflow within the pipe diminishing the heat conductance from the vacuumpump to the coolant.

Further, the aluminum blocks are assembled to the housing of the vacuumpump by alloy steel bolts at room temperature. During operation, thecooling block temperature cycles between usually 20 to 160° C. Since thealloy steel bolts have a lower thermal expansion than the aluminum,stress is induced into the bolts causing fatigue failure on the bolt.Thus, cooling effect can be diminished, and service of the vacuum pumpmay become necessary.

Thus, it is an object of the present invention to provide a coolingelement providing an efficient heat transfer of the heat to the coolantand performing its function more reliably.

A solution to the given problem is provided by the cooling elementaccording to claim 1 as well as the vacuum pump according to claim 13.

In accordance to the present invention the cooling element for vacuumpump comprises a base element wherein by the base element an internalvoid is defined. Further, an inlet is connected to the base element andis in fluid connection with the void. An outlet is connected to the baseelement and is in fluid connection with the void such that a coolant canflow from the inlet through the void to the outlet to dissipate the heattransferred from the housing of the vacuum pump to the coolant.Therefore, the base element is connectable to the housing of the vacuumpump. Due to the coolant flowing through the internal void of the baseelement heat produced by the vacuum pump is dissipated and reliablycarried away from the vacuum pump.

Preferably, the void is tubular. In particular the base element isprovided by a pipe for ease of construction. Therein, the pipes can beshaped in different forms in order to provide a sufficient length totransfer heat from the vacuum pump to the coolant.

Preferably, the void has a flat shape. In this sense flat means that theheight of the void is smaller than the width of the void. In particular,the width is more than twice as large as the height, preferably morethan four-times as large as the height and even more preferably morethan 10-times as large as the height. In particular, the height of thevoid is less than 3 mm, preferably less than 2 mm and even morepreferably less than 1 mm. In comparison the width of the void can beseveral tens of mm, preferably more than 25 mm and more preferably morethan 40 mm. Thus, by the flat void a large surface is created that is incontact with the coolant when the coolant is flowing through the void.Thus, efficiency of the heat transfer from the vacuum pump to thecoolant may be improved.

Preferably, also the base element has flat shape thereby reduction ofthe amount of material and thus the costs of fabrication may beachieved. Therein, the shape of the base element may be adapted to theshape of the void. Therein, the term flat has the same meaning, i.e.that the base element has a height which is much smaller than the widthof the element.

Preferably, the void has a length exceeding the width of the void,preferably exceeding the width of the a factor of two, more preferablyby a factor of 4 and most preferably by a factor of 8. Thus, the coolantmay have a sufficient time in order to take up the heat from the vacuumpump which is then dissipated by the coolant.

Preferably, the base element comprises a bottom surface to be directlyattached to the surface of the housing of the vacuum pump. Thus, thebase element is in direct contact with the housing of the vacuum pumpwhich may provide sufficient heat conductivity in order to transfer theheat from the housing of the vacuum pump to the bottom surface of thebase element, to the coolant in the internal void that is defined by thebase element. In particular, the bottom surface is flat in order providefull contact with the surface of the housing of the vacuum pump.

In particular, the material thickness between the bottom surface of thebase element and the void is less than 3 mm, preferably less than 2 mmand more preferably less than 1 mm. Thus, sufficient heat conductivitymay be provided. Even if the base element is made from stainless steel,there might be sufficient heat conductivity due to the small materialthickness of the bottom of the base element.

Preferably, the internal void comprises at least one corrugated surfaceto create turbulent flow within the void. Therein, the corrugatedsurface might be provided at least at the upper surface which is at theopposite site of the bottom surface away from the surface of the housingof the vacuum pump. More preferably, the upper surface as well as thebottom surface might comprise a corrugated surface.

Preferably, therein the corrugated surface can be provided by grooveswhich are arranged perpendicular to the direction of flow through thevoid. Alternatively or additionally, the corrugated surface might beprovided by ribs arranged perpendicular to the direction of flow. Thus,if only one corrugated surface is present, the corrugated surface can bebuilt as grooves or ribs. If two corrugated surfaces are present, thetwo surfaces can be built both with grooves or both with ribs or onecorrugated surface can be built as ribs and one corrugated surface canbe built as grooves.

Preferably, if no connecting element is present, the corrugated surfaceof the upper surface is built as grooves wherein the corrugated surfaceof the bottom surface is built as ribs. In particular, if the baseelement is surrounded by a connecting element as described below thenthe bottom surface may be built as grooves or ribs in order to ensureturbulent flow within the void. By the turbulent flow in the void heattransfer to coolant might be improved.

Preferably the features of the corrugated surface of the upper surfaceand the features of the corrugated surface of the bottom surface arearranged alternating along the direction of flow.

Preferably, a turbulator element is disposed within the void to createturbulent flow within the void. Preferably, the turbulator element isbuilt as wire mesh introduced into the void as separate element. Inparticular, if the void is constructed as pipe the turbulator elementcan be easily introduced into the pipes in order to ensure turbulentflow within the pipes enhancing the heat transfer to the coolant.

Preferably, the base element is built as one piece. Thus, there is nopossibility of leakage of the coolant. Alternatively, the base elementis composed of two pieces or more which are glued, welded, screwed orotherwise leaktight attached together.

Preferably, the base element is fabricated by 3D printing. Inparticular, if the base element is built in one piece by 3D printing itmay provide the possibility to create internal voids with complex shapessuch as a corrugated surface. Thus, 3D printing facilitates fabricationof the cooling element.

Preferably, the base element is surrounded by a connecting element. Inparticular, if the base element is not directly connected to the housingof the vacuum pump, the connecting element connects the base elementwith the housing of the vacuum pump. Therein, preferably, the connectingelement is made from aluminum wherein the connecting element is directlyconnected to the housing of the vacuum pump. Therein, the base elementcan be cast-in or pressed-in into the connecting element to providesufficient contact between the base element and the connecting element.

Preferably, the base element is made of stainless steel. In particular,if aggressive coolants are used stainless steel provides the benefit ofbeing in urge and long-lasting. Thus, if the cooling element is attachedby alloy steel screws, cooling element and screws have the same orsimilar thermal expansion. Thus, thermal stress induced might bereduced.

Further, the present invention relates to a vacuum pump comprising ahousing and cooling element as previously described.

The Summary is provided to introduce a selection of concepts in asimplified form that are further described in the Detailed Description.This summary is not intended to identify key features or essentialfeatures of the claimed subject matter, nor is it intended to be used asan aid in determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in detail with reference to theembodiments according to the accompanied drawings.

It is shown:

FIG. 1 a perspective view of the cooling element in accordance to thepresent invention,

FIG. 2 a cross section of the cooling element according to FIG. 1 ,

FIG. 3 another embodiment of the cooling element according to thepresent invention and

FIG. 4 an exemplary turbulator element.

DETAILED DESCRIPTION

The cooling element 10 according to the present invention comprises abase element 12 which is according to FIG. 1 built as flat base element12. Further, to the base element an inlet 14 and an outlet 16 isconnected. A coolant is flowing through the inlet 14 as depicted by thearrow 18, flowing through an internal void 20 built in the base element(FIG. 2 ) and leaving the cooling element 10 through the outlet 16 asdepicted by the arrow 22. Therein the base element 12 comprises a bottomsurface 24 which is in direct contact with the surface 26 of the housing28 of the vacuum pump as depicted in FIG. 2 .

Due to the flat shape of the void 20 in the base element 12 most of thecoolant is close to the bottom surface 24 and able to take up heatenergy transferred from the housing 28 of the vacuum pump to the coolingelement 10. Therein, the cooling element 10 might be built fromstainless steel. Even though stainless steel has a low heatconductivity, enough heat is transferred from the vacuum pump to thecoolant since the material thickness D between the bottom surface 24 ofthe cooling element 10 and the lower surface of the internal void 20 issmall and in particular less than 2 mm.

In accordance to the present invention an upper surface 30 of theinternal void 20 is built as corrugated surface by a plurality ofgrooves 32 which are perpendicular to the direction of flow (asindicated by arrow 34). In addition, the lower surface 31 of theinternal void 20 also comprises a corrugated surface as depicted in FIG.2 , wherein the corrugated surface in FIG. 2 is built by ribs 33arranged perpendicular to the direction of flow and interchangeablyarranged to the grooves 32 of the upper surface 30. Thereby, the coolantis forced into turbulent flow enhancing the possibility of the coolantto take up heat from the vacuum pump.

Preferably, the base element 12 is built as one piece by 3D printing.Thereby, the complex shape of the void 20 can be easily achieved andfurther a leak tight design is provided.

The method of fabrication of the cooling element comprises the steps of:

-   -   a) Printing a base element by 3D printing from stainless steel,        wherein the base element comprises an internal void; and    -   b) Attaching an inlet and an outlet to the base element in fluid        communication to the internal void either also by 3D printing of        any other method, such as welding, brazing or the like.    -   Therein the cooling element may have the features as described        above or below.

FIG. 3 shows another embodiment wherein the base element 12 comprises afirst corrugated surface 32 as the embodiment of FIGS. 1 and 2 and alsohas a second corrugated surface 36 opposite to the first corrugatedsurface 32 wherein both are built identically by grooves. Thus, theopposite surface, i.e. the lower surface defining the void in betweenare built as corrugated surfaces. Therein, the base element 12 is placedinto a connecting element 38 which is then connected to the surface 26of a housing 28 of the vacuum pump. Therein the base element 12 might becasted into the connecting element 28 which is preferably made fromaluminum. Thereby, both surfaces can be built as corrugated surfacesenhancing the possibility to take up heat by the coolant. In addition,features of FIG. 3 which are the same or similar to features of theformer figures are indicated by the same reference numbers.

Therein, in FIG. 3 , the flat base element is parallel arranged in theconnecting element 38 to the surface 26 of the housing of the vacuumpump. Therein, parallel means that the bottom surface 24 and/or the topsurface 30 of the base element 12 are parallel to the surface of thehousing of the vacuum pump. Alternatively, the base element 12 can bearranged perpendicular within the connecting element 38 relative to thesurface of the housing of the vacuum pump.

FIG. 4 shows a wire mesh turbulator as turbulator element 40 which canbe introduced into the void, in particular, if the void is built as pipein order to ensure turbulent flow within the void, i.e. pipe.

Although elements have been shown or described as separate embodimentsabove, portions of each embodiment may be combined with all or part ofother embodiments described above.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are described asexample forms of implementing the claims.

1. A cooling element for a vacuum pump, comprising a base element,wherein by the base element an internal void is defined, an inletconnected to the base element and in fluid connection with the void andan outlet connected to the base element and in fluid connection with thevoid such that a coolant can flow from the inlet through the void to theoutlet to dissipate heat, wherein the base element is connectable to ahousing of the vacuum pump, characterized in that the void has a flatshape such that the width of the void is more than twice as large as theheight of the void, and the height of the void is less than 3 mm. 2-3.(canceled)
 4. The cooling element according to claim 1, characterized inthat the base element has a flat shape.
 5. The cooling element accordingto claim 1, characterized in that the base element comprises a bottomsurface to be directly attached to the surface of the housing of thevacuum pump.
 6. The cooling element according to claim 5, characterizedin that the material thickness between the bottom surface and the voidis less than 3 mm, preferably less than 2 mm and more preferably lessthan 1 mm.
 7. The cooling element according to claim 1, characterized inthat the internal void comprises at least one corrugated surface tocreate turbulent flow within the void.
 8. The cooling element accordingto claim 1, characterized by a turbulator element disposed within thevoid to create turbulent flow within the void.
 9. The cooling elementaccording to claim 1, characterized in that the base element is onepiece.
 10. The cooling element according to claim 1, characterized inthat the base element is fabricated by 3D printing.
 11. The coolingelement according to claim 1, characterized in that the base element issurrounded by a connecting element, preferably made from aluminum,wherein the connecting element is directly connected to the housing ofthe vacuum pump.
 12. The cooling element according to claim 1,characterized in that the base element is made of stainless steel.
 13. Avacuum pump comprising a housing and a cooling element according toclaim 1 connected to the housing.